Electrical circuit interrupter having exterior positioned actuating means



Jan. l2, 1965 l. J GOLDBERG 3,165,610

ELECTRICAL. IRCUIT INTERRUPTER HAVING EXTERIOR POSITIONED ACTUATING MEANS Filed Sept. 6, 1962 A United States Patent O 3,165,610 ELECTRICAL ClRGClUlT NTERRUPTER llilAtflNG EXTERIGR PGSE'EHNED ACTUATWG MEANS Leon l. Goldberg, Schenectady, NX., assigner to General Electric Company, a corporation of New York Filed Sept. 6, w62, Ser. No. 221,755 4 Claims. (Cl. Zitti- 150) My invention relates to an apparatus `for interrupting an electrical circuit and, in particular, to an apparatus for suppressing or extinguishing an electrical arc within a iluid filled sealed container wherein actuated or arc interrupting elements are Ipositioned within the container and actuating means for operating the actuated elements are magnetically coupled thereto and positioned without the container.

Circuit interrupters find use in electrical circuits wherein an interruption of power flow must be achieved in a short interval of time in response to a particular circuit condition. Thus, circuit interrupters are utilized throughout the range of electrical circuitry from electronic circuits operable at less than one watt of electrical power to industrial and utility networks involving thousands of kilowatts of power. Low power circuit interrupters, in general, are characterized by a very small arc formation between the interrupting terminals or contacts of the apparatus during the time interval wherein the electrical circuit is undergoing interruption. The small arc usually presents little difiiculty in effecting circuit interruption. However, interruption of higher ,power circuits, in general, produces a much more extensive arc, and until this arc is completely extinguished, the circuit remains uninterrupted. As a consequence, conventional lhigh power circuit breakers are designed to produce arcs of such dimensions and under such environments that an instability occurs, whereby the arc requires more voltage than the circuit can supply thereby causing the current to decrease.

`T his instability is usually attained by lengthening the arc between the opened contacts and confining the arc with the air of arc chutes and arc horns. In direct current circuit interruption, maintaining this kind of instability forces the current to zero, causes arc suppression and extinction, and circuit interruption. Conventional interrupters operating on alternating current circuits do not substantially suppress the arc because it is easier to allow the arc to exist until the alternating current reaches a subsequent zero value and then be prevented from re-establishing itself after the current zero. The arc becomes suppressed when the arc lengthening and confining action has forced the arc to give up more encrgy than the circuit at the arc voltage can supply. Re-ignition is prevented by operation of' a similary structure in promoting deionization between the open ,contacts to the degree whereat the breakdown gap voltagebetween the open contacts exceeds the voltage that the circuit will apply thereacross. Air blast or oil blast accessory devices are also often employed to literally blow out the arc by a cooling and arc lengthening or arc dispersin-g action. At high power levels, arc chutes and arc horns become large, cumbersome, and expensive; air blast accessory devices add further expense; and oil blast accessory devices add both further expense and a fire hazard. Also, during the contact opening interval in conventional high power oil filled circuit breakers, there is generally either a displacement of some of the oil therein or the pressure developed by the oil has a significant effect on the actuating member thereby increasing the circuit interruption time. Since conventional circuit interruption apparatus in the higher power ranges become particularly large and expensive, a need exists for solving this probn Patented Jan. 12, 1965 ice lem by providing a new apparatus for interrupting electrical circuits. v

Therefore, one of the principal objects of my invention is to develop a new and improved apparatus for interrupting the flow of power in an electrical circuit.

Another important object of my invention isto develop a new and improved apparatus wherein electrical circuit interruption is developed in a compact sealed chamber.

A .further important object of my invention is to develop a new and improved apparatus of the electrical cir cuit interrupting type where in an actuated member is located within a sealed chamber and the actuating member is located without.

A still further important object of my invention is to develop a new and improved apparatus for interrupting either direct current or alternating current power wherein the actuated and actuating members are magnetically coupled.

Briefly stated, and in accordance with one aspect of my invention in meeting the objects enumerated above, I provide a sealed chamber wherein is disposed an actuated member for developing an arc for the purpose of effecting a circuit interruption. The chamber may be evacuated to a high vacuum or substantially filled with a fluid medium and an actuating member responsive to external circuit conditions is disposed without the chamber and magnetically coupled to the actuated member for the purpose of initiating its operation.

The features of my invention which I desire to protect herein are pointed out with .particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may be understood by reference to the following description taken in connection with the accompanying drawing, wherein like parts in each of the several figures are identified by the same reference character, and wherein:

FIGURE l is an elevation view, partly broken away, illustrating a double break contact and double coil actuating embodiment of a circuit interrupter apparatus constructed in accordance with my invention; and

FIGURE 2 is `a plan view illustrating the apparatus shown in FIGURE l.

The apparatus of my invention is adapted to combine the principles of both direct current and alternating current power circuit interruption in that it effects suppression of the arc and also prevents re-ignition after a current zero in the alternating current case. Referring particularly to the apparatus illustrated in FIGURES l and 2, there is shown a sealed chamber or vessel designated as a whole by numeral l wherein the outer surface may have any convenient shape and the inner surface preferably has a hemispherical shape in the upper portion thereof. Chamber l comprises two sections, an upper or housing member 2 containing the hemispherical inner surface and a lower or base plate member 3. Housing member 2 is constructed of a strong material, such as steel or iron, in order to withstand the pressures developed within the chamber during arc interruption. Base plate member 3 is made of a non-magnetic metal, such as bronze, brass, or nonmagnetic steel. Housing member 2 is fastened to base plate member 3 by means of several conventional bolt and washer arrangements 4, only one being shown. A gasket type member, such as an O-ring 5 made of rubber, or other suitably plastic and resilient material, assures a pressure type hermetic seal between housing member 2 and base plate member 3. Sealed chamber l is connected to a supporting member by means of rod 6, which is fastened to base plate member 3 with a conventional bolt and washer arrangement 7. Rod 6 may comprise any material whereby the rod will adequately support the weight dieser@ of the circuit interruptor and is preferably constructed of an electrically insulating material since base plate member 3 may be at line potential. The means for fastening housing member 2 and rod 6 to base plate member S is not limited to the bolt and washer arrangement and may comprise any suitable fastening means that achieves a iirin joint.

A circuit interrupter actuating means designated as a whole by numeral 8 is positioned without sealed chamber ll whereas an actuated means designated as a whole by numeral 9 is positioned within. Actuating means S is magnetically or inductively coupled to actuated means 9 by means of magnetic inserts lill which may be made of magnetic steel and comprise a lower portion passing through base plate member 3 and an upper shoulder portion contained within the enclosed chamber. inserts are intimately and strongly joined to base plate member 3 by any convenient method, such as bracing. Actuating means 3 comprises a pair of cylindrical magnetic core portions il, as seen in FlGURE 2, which may be manufactured from mild carbon steel, on each of which is wound a coil l2. Coil l2 may be electrically connected in a pushbutton circuit for manual control of circuit interruption or connected to a device which senses abnormal or predetermined circuit conditions for an automatic mode of control. Coil l2 is retained in place on core il by magnetic plate i3 on one end thereof and spring washer la on the other end with a bolt and washer arrangement l5 passing through magneticy plate lll and core lll. and into insert l@ to provide a firmly secured magnetic circuit. ln the alternative, core ill may be welded to insert itl, fastened thereto by a stud integral to core il, or core lli and insert lltl may comprise a vunitary piece, and bolt i5 merely passes into a lower portion of core lli thereby improving its magnetic properties.

vActuated means 9 comprises a magnetic armature lo which operates a movable contact i7 into open or closed circuit position with a pair of fined contacts ld in response to deenergization or energization of coils llZ. lt must be understood that the number of fixed contacts in actuated means 9, and coils l2 in actuating means d is a matter of design dictated by several considerations which do not affect the principle of this invention. Thus, employing only one fixed contact i3 in a single break circuit within sealed chamber il necessitates the use of a tlexible conductor that is connected at one end to the movable contact i7 and brought out through the wall of the chamber whereas employing two fixed contacts in a double break circuit requires no flexible conductor and may be brought out of the chamber in a manner to be described in detail hereinafter. The two fixed contact, two-coil embodiment is further preferred since a simple pivot may then be employed for the movable contact. ln the preferred embodiment, and as is more clearly illustrated in the plan View of FlGURE 2, actuating means tl comprises two spaced apart magnetic core legs il and magnetic inserts l@ with a separate coil l2 wound on each core leg. Magnetic plate i3 engages both coils l2 and cores lll thereby completing the magnetic path through core legs il and arma* ture ld. Armature ld comprises a solid body of a suitable magnetic material such as mild carbon steel and has a nonmagnetic shim l@ joined thereto or at the surface of magnetic insert l@ to develop a predetermined air gap in the magnetic path and thereby prevent retention in the closed position by reason of residual flux within core lll.. ln the closed circuit position, armature l@ extends across and contacts the surfaces of both magnetic inserts itl. An energizing of coils l2 attracts armature lo electromaglnetically or inductively, thereby causing armature lr6 to pivot in a clockwise direction about hinge pin 2d and come into contact with the surface of magnetic inserts lll. Two metallic brackets 2l are welded to base plate member 3 and among their functions act as retaining means for hinge pin Ztl. A second bracket 22. having a generally U-shape in cross section is welded at surface to armaits ture lo. Thus, when coils l2 are dec ergized for purposes of circuit interruption, armature le and bracket 22 are cause to pivot about hinge pin in a counterclockwise direction by spring 57 in a manner to be described in detail hereinafter. Fixed contacts lb comprise two spaced apart copper contacts whichmay have contact faces of tungsten impregnated with silver or other suitable Contact material brazed thereon. Each fixed Contact lll is connected to base plate member 3 by means of an insulation plate 2d and a bolt passing through the base plate, '.isulation plate, and a'portion of the fixed contact. insulation plate 2d may be composed of a molded or lami nated plastic insulation such as filled phenolic resin or other suitable electrically insulating material appropriate to the voltage of the external electrical circuit, A shoulder portion of insulation plate 7.4 acts as a further aligning means for contacts lill. Bolt 2o is electrically insulated from base plate member 3 by means of bushing 27, made of an electrically nonconductive material. A pressure type hermetic seal connection between liked contacts i3 and insulation plate 2d and also between insulation plate 24 and base plate member 3 is assured by means of O-rings Ztl and T39, respectively, wherein the rings may be made of the same material as Q-ring 5. Two power conductors 3d, whi h form part of the electrical circuit being interrupted, are electrically connected to the iixed contacts ld by means of bolts Z6 and electrically insulated from base plate member 3 by means of insulation plate 3l which may be made of the same material as rinsulation plate 24. ln the alternative, bushing and insulation plate Tbl may comprise a unitary member. Relatively movable contact T17 is supported on bracket 2,2 and comprises a body of copper which may also be faced with a suitable electrical contact material and is of sufficient dimension to mate with both fixed contacts ld when in closed circuit position. Pin 52 having retaining washers on each end thereof passes through a bridging portion 33 of movable contact i7 and through contact supporting bracket 22,. The lower washer (not shown) engages bracket 22 on its lower surface andl upper washer 3d engages a steel spring 35 maintained under greater compression when in closed circuit position for resilient mounting of Contact l'to effect a positive mating of the face surfaces of contact il and contacts iS. An end portion of bracket 22 acts asa guide to maintain alignment of movable contact f7 with stationary contacts lltl.

Relatively movable contact il? is operated into an open circuit position upon de-energization of coils i2 by means of armature le, bracket Z2, spring 37, and stop member Titi. Spring 37, having one end engaging contact supporting bracket Z2, is in greater compression during the closed circuit position of the contacts as shown by the full lines in FlGURES l and 2. Upon de-energization of coils l2, armature i6 is no longer attracted to magnetic inserts lill, and spring 37 thereafter expands thereby pivoting armature l@ andcontact supporting bracket 22 in a counterclockwise direction about hinge pin into the yopen circuit position as shown by the phantom lines in FIGURE l. Metallic member is welded to the two opstanding portions of bracket Zi and has a recess 40 therein for the guidance of spring 37. The opposite side of spring 37 is retained on bracket 2.2 by means of a shoulder portion di. The extent of counter-clockwise motion of bracket 22 is limited by stop member 38, the amount of motion being controllable by varying the position or stop member 3S with respect to lined member 39 in any well-known manner. Thus, by way Vof illustration, stop member E@ may be connected to fixed member 39 with adjusting screws d2 w ich are threaded into member 39 and pass through adjusting slots i3 in member 38;.

The interior of sealed chamber ll may contain a vacuum or a iiuid, the particular fluid employed being determined by the following considerations. The electrical arc formed on parting of the contacts heats the surrounding iiuid and since the duid cannot escape, it passes through some or all of the following changes of state: vaporization, decomposition into simpler compounds, decomposition into elements, dissociation, ionization. Since it is desired to regenerate these products back to the original fluid after arc extinction to permit repetitive operation of the circuit interruption apparatus, a fluid that is both dissociable and recombinable must be employed. A lluid comprising a liquid form of a relatively inert gas, such as nitrogen, or an absolutely inert gas such as helium, satisfies the requirements since the single element will return to its original state. Liquid hydrogen may also be employed. A liquid, such as water, splits into hydrogen and oxygen gas which recombines into water due to the prevailing pressure and temperature developed by the arc. The recombination of the hydrogen and oxygen may be further assured by the addition of'a catalyst, suchV as plat-l inum black, placed into the vessel. If the lluid completely fills the chamber and has no dissolved gas or Volatile impurity therein, the electrical conduction initiated by an arc formation between opening contacts 17 and l takes place within the fluid in liquid form or in a bubble of its gas at a pressure above the critical pressure of the fluid. This condition develops a very high arc voltage and pressure, causing excessively fast circuit interruption which produces undesirable Voltage surges. Thus, it is desirable to provide an initial vapor space or its equivalent by displacement wherein the arc may form and be subsequently suppressed and extinguished. The initial vapor space may be provided by not filling sealed chamber 1 completely with the fluid and leaving a very small space therein. Upon arc formation between the contacts 1'7 and 18, the initial vapor space will be displaced by a gas produced between the conducts due -to the arc dissociating the fluid therebetween. By this method circuit interruption is controlled with respect to voltage surge and speed of circuit interruption. Optionally, a collapsible capsule, such as an enclosed bellows arrangement or a piece of sponge rubber or other elastomer with closed pores may be attached to an inner wall of sealed chamber l wherein it will not interfere with the operating mechanism, and sealed chamber 1 may be completely filled with fluid. Thus, upon initial arc formation between the parting contacts, the bellows or sponge rubber becomes compressed, thereby providing the necessary vapor space between the contacts for the gas being generated by the dissociating liquid. Further, the lluid may be confined and pressure controlled within sealed chamber l by employing a biased or pre-loaded collapsible capsule, such as a sealed spring loaded bellows. In this case, the initial vapor space forms rapidly to a volume determined by the spring pre-loading and then at a retarded rate until the capsule is fully compressed. Thus, a means may be provided for retarding the rate of arc voltage rise either initially on parting the contacts or later as desired.

The liquid which becomes dissociated into high pressure gaseous products between the parted contacts in response to an arc therebetween has the effect of compactly coniining the arc within this narrow region defined by high pressure gas. The characteristics of the high pressure gas cause the arc to have a high voltage gradient and to deionize the space between the contacts rapidly after the arc extinguishes. The characteristics of the small volume within which the arc forms cause the arc to develop a high voltage gradient due to the efficient heat transfer to the bounding liquid and to rapidly deionize the corresponding space after arc extinction for the same reason. Thus, these factors of high pressure gas and liquid which is at the same high pressure, and compact confinement of the arc produce an elective arc suppression and effectively prevent re-ignition after arc extinction. The dissociation of the liquid into gaseous products also absorbs energy from the arc, thereby further aiding to suppress it. Thus, a circuit interrupter in accordance with my invention will interrupt compactly both direct current power and greater values of alternating current power as in conventional a fluid.

vinterrupter apparatus, since it is easier to deionize gas at current zero than during current ilow.

The predetermined vapor space between the parting contacts wherein the arc is produced and suppressed should be controlled as to volume thereof for the most effective interruption characteristics. Hence, it can be appreciated that the prevention of any other net displacement of fluid within vessel Il due to mechanical actuation is very desirable. Thus, by transmitting the contact actuating forces from an operating magnet on the outside of the vessel through the wall thereof to an armature inside in accordance with my invention, a very etlicient interrupter having predetermined interrupting characteristics is obtained. Another advantage of this arrangement is that any pressure developed by the iiuid inside the vessel has no primary effect on the work required from the magnet. Further, by placing the actuating means outside the vessel, additional leads need not be brought within the vessel and coils 12 cannot be damaged by the luid therein.

As a second embodiment of my invention, chamber ll is evacuated to a high vacuum instead of being filled with Interruption under these conditions is effected primarily for alternating current power. When the contacts part, a metallic vapor arc forms which carries current, and at the first subsequent current zero the metallic vapor is very rapidly deionized, dispersed, and condensed in the high vacuum and thus prevents the arc from reforming. The advantage of this apparatus is that a structure can be readily made to include components suitable for high vacuum around the contacts, and a separate actuator that cannot be readily made to be placed in a high vacuum operates the contacts without employing conventional sealed mechanically actuated couplings.

For very high power applications, short arc horns may be attached to the contacts to lengthen the arc, thereby aiding in its suppression. It should be noted that the arc horns used in this application would be considerably shorter than the arc horns necessary in a conventional circuit interrupter apparatus having the same power rating since the arc travels much slower through the confined iiuid. Further, a magnetic field may be employed to cause the arc to move on the contacts either along the length of arcing horns provided for this purpose, or to spin repetitively in a circular orbit, to aid in cooling the contacts, and also to cool the arc. The contacts are cooled since the arc movement minimizes the concentration of heating of any one spot on each contact and the arc is cooled since the arc will form in fresh fluid as it advances through the iluid in a manner similar to driving fluid past a stationary are.

From the foregoing description it can be appreciated that my invention makes available an improved apparatus for the interruption of electrical power wherein an actuating means is located outside of a compact sealed chamber and actuated or circuit interrupting means -is located within the chamber which is substantially filled with a dissociable and recombinable fluid or evacuated to a high vacuum. VThis circuit interrupting apparatus provides a more economical method of circuit interruption than provided by conventional circuit interrupters since the device is lvery compact especially in the higher power ratings.

Having described two embodiments of a new and improved apparatus for interrupting electrical power circuits, it is believed obvious that modications and variations of my invention are possible in light of the above teachings. The novel feature of having an actuated means within a sealed chamber and an actuating means without and magnetically coupled thereto, is not limited to the particular embodiment of actuated and actuating means disclosed hereinabove; The particular single movable, double stationary contact, double coil arrangement has been illustrated merely as one example of an actuated and actuating means that may be utilized in my invention and alternative arrangements well known in the art, such as single break contacts and single coils can also be employed. Thus, the

diedero teachings may also be applied to a fuse type of interruptor having fixed contacts or electrodes connected by a fusible l link, all confined within the liuid. lt is, therefore7 to be understood that changes may be made in the particular embodiment of my invention described which are within the full intended scope of the invention as defined by the following claims.

What l claim as new and desire to secure by Letters Patent oi the United States is:

l. A compact electrical circuit interruptor comprising a base plate member, Y

actuated means comprising a relatively movable contact, a pair of stationary contacts, and a magnetic armature Jfor operating said movable contact into open and closed circuit position with said stationary contacts,

a totally enclosed compact container,

a dissociable iluid coniined within said container, lsaid actuated means positioned within said container and immersed within said duid, said fluid dissociating into a gaseous medium in a region between the contacts in response to productionoi an electric arc therebetween, said gaseous medium forming at high pressure by reason ot a fixed volume of iiuid and gas in said vessel whereby the arc becomes extinguished and thereby interrupts the electrical circuit, said gaseous medium thereafter recombining in absence of the arc to form the original fluid, and

actuating means for operating said actuated means and magnetically coupled thereto, said actuating means disposed without said container and comprising two spaced apart magnetic core legs and coils wound thereon,

magnetic inserts joined to each core leg, said inserts including a first portion passing through said base plate member and a shoulder portion contained within said container,

a nonmagnetic shim positioned between the shoulder portion of said inserts and said armature whereby said nonmagnetic shim is in contact with said shoulder portion and said armature during closed circuit position of said movable and stationary contacts to velop a predetermined air gap in the magnetic path and thereby prevent retention ot said movable con tact in the closed circuit position by reason of residual hun in said core legs, energization of said coils causing said armature to pivot and thereby communicate with said magnetic inserts to move said movable contact into closed circuit position.

2. An electrical circuit interrupter comprising a base plate member, 1

actuated means for opening and closing an electrical circuit, said actuated means comprising a pair of stationary contacts and a relatively movable contact, said relatively movable contact having two contact making surfaces and a bridging portion therebetween,

a magnetic armature for operating said movable contact into open and closed circuit position with said vstationary contacts,

a hinge pin in communication with one end of said armature for pivoting said armature,

first bracket means connected to said base plate member for retaining said hinge pin,

a second bracket connected to said armature, said relatively movable Contact supported on said second bracket, said second bracket having an end portion to maintain alignment of said movable Contact with said stationary contacts,

a spring having one end thereof supported on said sccond bracket, said spring in greater compression during closed circuit position ot said movable and stationary contacts, said spring expanding upon deenergization of coils in an actuating means `for said interruptor thereby pivoting said armature and said second bracket about said hinge pin to operate said movable Contact into open circuit position,

a ermetically sealed compact container,

a dissociabie 'luid conlined within said container, said actuated means positioned within said container and immersed within said iiuid, said fluid dissociating into a gaseous medium in a region between the contacts in response to production of an electric arc therebetween, said gaseous medium forming at high pressure by reason et a iixed volume of iiuid and gas in said vessel whereby the are becomes extinguished and thereby interrupts the electrical circuit, said gaseous medium thereafter recombining in absence of the arc to form the original fluid, and

actuatin means for operating said actuated means and insuctively coupled thereto, aid actuating means disposed outside said container.

3. An electrical circuit interruptor comprising a base plate member,

actuated means for opening Vand closing an electrical circuit, said actuated means comprising a pair of stationary contacts and a relatively movable contact, said relatively movable contact having two contact making surfaces and a bridging portion therebetween,

a magnetic armature for operating said movable contact into open and closed circuit position with said stationary contacts,

a ringe pin in communication with one end of said armature for pivoting said armature,

rst bracltet means con ected to said base plate member for retaining said hinge pin,

a second bracket connected to said armature, said relau tively movable contact supported on said second bracket, said second bracket having an end portion to maintain alignment or" said movable contact with said stationary contacts,

a spring having one end thereof supported on said sec-j ond bracket, said spring in greater compression during closed circuit position of said movable and stationary contacts, said spring expanding upon de- .tion or coils in an actuating means for said interrupter thereby pivoting said armature and said second bracket about said hinge pin to operate said movable contact into open circuit position,

a sealed compact vessel, said actuated meansv disposed within said vessel,

a dissociable and recombinable tluid substantially filling said vessel, said actuated means immersed within said iiuid, and

actuating means for operating said actuated means and inductively coupled thereto, said actuating means disposed without said vessel and comprising two spaced apart magnetic core legs and coils wound thereon,

magnetic inserts joined to each core leg, said inserts including a iirst portion passing through said base plate member and a shoulder portion contained witbin said vessel,

a nonmagnetic shim positioned between the shoulder portion of said inserts and said armature whereby said nonrnagnetic shim is in contact with said shoulder portion and said armature during closed circuit position of said movable and stationary contacts to develop a predetermined air gap in the magnetic path and thereby prevent retention of said movable contact in the closed circuit position by reason of residual 'lux in said core legs, energization of said coils causing said armature to pivot about said hinge pin and thereby communicate with said magnetic inserts to move said movable Contact into closed circuit position.

4. A compact electrical circuit interruptor comprising 75 a base plate member,

actuated means for opening and closing an electrical circuit, said actuated means comprising a pair of stationary contacts and a relatively movable contact, said relatively movable contact having two contact making surfaces and a bridging portion therebetween,

a magnetic armature for operating said movable Contact into open and closed circuit position with said stationary contacts,

a hinge pin in communication with one end of said armature for pivoting said armature,

tirst bracket means connected to said base plate member for retaining said hinge pin,

a second bracket connected to said armature, said movable contact supported on said second bracket, said second bracket having an end portion to maintain alignment of said movable contact with said stationary contacts,

a second pin having retaining means on each end thereof, said second pin passing through the bridging portion of said movable contact and through said second bracket in engaging relationship thereto at a first end thereof,

a rst spring engaged by a second end of said second pin and maintained under greater compression during closed circuit position of said mov-able and stationary contacts for resilient mounting of said movable contact to effect positive mating of the contact making surfaces of said movable and stationary contacts,

a second spring having a rst end thereof supported on said second bracket and a Second end retained in a lixed position by means of a recessed member joined to said first bracket, said second spring in greater compression during closed circuit position of said movable and stationary contacts, said second spring expanding upon deenergization of coils in an actuating means for said interrupter thereby pivoting said armature and said second bracket about said hinge pin to operate said movable contact into open circuit 4 position, a sealed compact chamber, said actuated means disposed within said chamber,

a medium contained within said chamber, said medium being different from the outside atmosphere, and actuating means for operating said actuated means and magnetically coupled thereto, said actuating means disposed Without said chamber and comprising two spaced apart magnetic core legs and coils wound thereon,

magnetic inserts joined to each core leg, said inserts including a first portion passing through said base plate member and a shoulder portion contained Within said chamber,

a nonmagnetic shim positioned between the shoulder portion of said inserts and said armature whereby said nonmagnetic shim is in contact with said shoulder portion and said armature during closed circuit position of said movable and stationary contacts to develop a predetermined air gap in the magnetic path and thereby prevent retention of said movable contact in the closed circuit position by reason of residual flux in said core legs, energization of said coils causing said armature to pivot about said hinge pin and thereby communicate with said magnetic inserts to move said movable contact into closed circuit position.

References Cited bythe Examiner UNITED STATES PATENTS 1,375,983 4/21 Thomson 200-87 1,532,081 3/25 Rankin 200-150 1,706,746 3/29 Rice 200--148 2,108,560 2/38 Kesselring 200-148 2,323,702 7/43 Berkey 200-87 2,742,597 4/ 56 Penlington 200-144 2,843,698 7/58 Knauth 200-144 2,912,539 1l/59 Jennings 200--87 3,048,678 8/62 Reed et al ZOO-103 FOREIGN PATENTS 430,968 6/ 26 Germany. 1,210,923 10/59 France.

BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. A COMPACT ELECTRICAL CIRCUIT INTERRUPT COMPRISING A BASE PLATE MEMBER, ACTUATED MEANS COMPRISING A RELATIVELY MOVABLE CONTACT, A PAIR OF STATIONARY CONTACTS, AND A MAGNETIC ARMATURE FOR OPERATING SAID MOVABLE CONTACT INTO OPEN AND CLOSED CIRCUIT POSITION WITH SAID STATIONARY CONTACTS, A TOTALLY ENCLOSED COMPACT CONTAINER, A DISSOCIATED FLUID CONFINED WITHIN SAID CONTAINER, SAID ACTUATED MEANS POSITIONED WITHIN SAID CONTAINER AND IMMERSED WITHIN SAID FLUID, SAID FLUID DISSOCIATING INTO A GASEOUS MEDIUM IN A REGION BETWEEN THE CONTACTS IN RESPONSE TO PRODUCTION OF AN ELECTRIC ARC THEREBETWEEN, SAID GASEOUS MEDIUM FORMING AT HIGH PRESSURE BY REASON OF A FIXED VOLUME OF FLUID AND GAS IN SAID VESSEL WHEREBY THE ARC BECOMES EXTINGUISHED AND THEREBY INTERRUPTS THE ELECTRICAL CIRCUIT, SAID GASEOUS MEDIUM THEREAFTER RECOMBINING IN ABSENCE OF THE ARC TO FORM THE ORIGINAL FLUID, AND ACTUATING MEANS FOR OPERATING SAID ACTUATED MEANS AND MAGNETICALLY COUPLED THERETO, SAID ACTUATING MEANS DISPOSED WITHOUT SAID CONTAINER AND COMPRISING TWO SPACED APART MAGNETIC CORE LEGS AND COILS WOUND THEREON, MAGNETIC INSERTS JOINED TO EACH CORE LEG, SAID INSERTS INCLUDING A FIRST PORTION PASSING THROUGH SAID BASE PLATE MEMBER AND A SHOULDER PORTION CONTAINED WITHIN SAID CONTAINER, A NONMAGNETIC SHIM POSITIONED BETWEEN THE SHOULDER PORTION OF SAID INSERTS AND SAID ARMATURE WHEREBY SAID NONMAGNETIC SHIM IS IN CONTACT WITH SAID SHOULDER PORTION AND SAID ARMATURE DURING CLOSED CIRCUIT POSITION OF SAID MOVABLE AND STATIONARY CONTACTS TO DEVELOP A PREDETERMINED AIR GAP IN THE MAGNETIC PATH AND THEREBY PREVENT RETENTION OF SAID MOVABLE CONTACT IN THE CLOSED CIRCUIT POSITION BY REASON OF RESIDUAL FLUX IN SAID CORE LEGS, ENERGIZATION OF SAID COILS CAUSING SAID ARMATURE TO PIVOT AND THEREBY COMMUNICATE WITH SAID MAGNETIC INSERTS TO MOVE SAID MOVABLE CONTACT INTO CLOSED CIRCUIT POSITION. 